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標題: ZINCTOLERANCE INDUCEDBYIRON 1 reveals the importance of glutathione in the cross-homeostasis between zinc and iron in Arabidopsis thaliana
作者: Shanmugam, Varanavasiappan
Tsednee, Munkhtsetseg
Yeh, Kuo-Chen
關鍵字: Arabidopsis thaliana;c-glutamylcysteine synthetase;glutathione;zinc tolerance;iron;phytochelatin
Project: Plant Journal, Volume 69, page(s) 1006–1017.
Zinc is an essential micronutrient for plants, but it is toxic in excess concentrations. In Arabidopsis, additional
iron (Fe) can increase Zn tolerance. We isolated a mutant, zinc tolerance induced by iron 1, designated zir1,
with a defect in Fe-mediated Zn tolerance. Using map-based cloning and genetic complementation, we
identified that zir1 has a mutation of glutamate to lysine at position 385 on c-glutamylcysteine synthetase
(GSH1), the enzyme involved in glutathione biosynthesis. The zir1 mutant contains only 15% of the wild-type
glutathione level. Blocking glutathione biosynthesis in wild-type plants by a specific inhibitor of GSH1,
buthionine sulfoximine, resulted in loss of Fe-mediated Zn tolerance, which provides further evidence that
glutathione plays an essential role in Fe-mediated Zn tolerance. Two glutathione-deficient mutant alleles of
GSH1, pad2-1 and cad2-1, which contain 22% and 39%, respectively, of the wild-type glutathione level, revealed
that a minimal glutathione level between 22 and 39% of the wild-type level is required for Fe-mediated Zn
tolerance. Under excess Zn and Fe, the recovery of shoot Fe contents in pad2-1 and cad2-1 was lower than that
of the wild type. However, the phytochelatin-deficient mutant cad1-3 showed normal Fe-mediated Zn
tolerance. These results indicate a specific role of glutathione in Fe-mediated Zn tolerance. The induced
accumulation of glutathione in response to excess Zn and Fe suggests that glutathione plays a specific role in
Fe-mediated Zn tolerance in Arabidopsis. We conclude that glutathione is required for the cross-homeostasis
between Zn and Fe in Arabidopsis.
DOI: 10.1111/j.1365-313X.2011.04850.x
Appears in Collections:生命科學系所

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